1. Field of the Invention
The present invention relates to an ultrafiltration unit for the separation of colloidal or very fine solid material by filtration through microporous or semipermeable mediums.
2. Description of the Prior Art
There has been provided an ultrafiltration unit which is designed to pass a sample, e.g., a plasma sample, through a microporous or semipermeable filter, so-called an ultrafilter, and to make a protein-free plasma sample by separating protein through the ultrafilter. Such prior ultrafiltration unit comprises a wineglass-shaped member with an ultrafilter disposed therein. There is formed a chamber under the filter and a stem portion of the member is made of a hollow pipe having a bore therein which communicates with the chamber under the filter. The bore of the stem pipe is, at its free end, flared so as to be press fitted over a snout of a syringe in a manner so-called Leur taper coupling. The ultrafiltration is effected in this prior unit such that, after attaching the snout of the syringe to the stem pipe of the unit, a liquid sample, e.g., a plasma sample is poured onto the filter rested in the unit, and then a plunger of the syringe fixed to the stem pipe of the unit is pulled, so that there is produced a vacuum in the chamber formed underneath the filter in the unit. As a result, the sample percolates the filter by the atmospheric pressure and oozes out into the syringe.
In this conventional unit, however, there is a disadvantage that there is no way of restoring a vacuum condition once again when the vacuum in the chamber loses during the ultrafiltration, since it is no longer possible to reciprocate the plunger of the syringe after the same has been fixed to the stem pipe of the unit.
There is another disadvantage that there is further needed a supporting means, such as a stand, for holding the syringe, since the plunger of the syringe must be kept pulled during the ultrafiltration.
Further, there is a disadvantage that, since a filtered sample is collected in the syringe, there is required a further step to empty the sample into a test tube for a test in the next stage, which results in a considerable amount of loss of the sample.